Friction gear



Qct. 1 3, 1.936.

Rl ERBN FRICTION GEAR Filed oct. 21, 1955 4 4Sheets-Shee'c. 1

` ATTORNEY.

0a. 13, 1936. R, ERBAN 2,057,482 FRCTION GEAR Filed Oct. 21, 1935 4 Sheets-Sheet 2 I 44' .15-5. l Y l fo 42 4 O 42 O A 54 4o E 4 a ly l 36 A l 34 f v 1 u d o l `41 .7- fss T 'T T gg 'l .l l -l l 15 l' 38 Y 18 a I 18a 52 INVENTOR r. 'Rmx-iam: ERB am.

ATTORNEY.

Odi. 13, 1936. R ERBAN 2,057,482

FRICTION GEAR INVENT OR.

ATTORNEY.

'RICE-:ann ERERN BY lle,

R. ERBAN FRIC'I'ION GEAR Filed oct'. 21, 19:53

4 SheejtS-Sheet 4 m 8 ,E a v 3 m Run-1am: ERBHN.

ATTORNEY.

'Patented oct. 13, 193s UNITED STATES intim Partnr. ortica FRICTION GEAR Richard Erban, Vienna, Austria, assigner to Erben Patents Corporation, a corporation of New York Application October 21, 1933, Serial No. 694,633 In Austria February 3, 19,33

22 claims. (ol. 'r4- 281) variations in speed ratio are obtained either by ,A

shifting the friction disks along the common axis of the shafts, or by axially shifting the friction wheels relative to the friction disks, and every change in the gear ratio necessitates a change in the pressure of the friction disks against the friction wheels in order that the gear may operate at highest efiiciency for transmission of power. In other words, the higher, the gear ratio the greater is the required pressure between the friction disks and the friction wheels, and the lower the gear ratio the lesser is the required pressure between the friction disks and the friction wheels to assure transmission of any given torque without slippage between the friction wheels and the friction disks. Therefore, it

is not conducive to efficiency or longevity of a friction gear of the type mentioned to have the friction disks urged against the friction wheels under a single, unvarying pressure for different ratios of the gear, as this would result in inaclemitted by the gear. However, according to allA prior pressure varying arrangements operating onthis principle, the pressure is properly varied in response to differences in the, torque transmitted only for a single, definite speed ratio of the gear, and .for all other speed ratios of the gear the pressure variation is incorrect. Accordingly, the generalnobject of the present invention is to provide, in a friction gear of the type mentioned, novel and practical means whereby the pressure of the friction disks against the friction wheels -is properly maintained according to the torque vtransmitted and for all speed ratios` of the gear.

With the foregoing and various other objects in view, which will become more fully apparent as thenature of fthe invention is better understood, the same consists in the novel combination and arrangement of features as will be hereinafter more fully described, illustrated in the accompanying drawings and defined in the appended claims.

In the drawings, wherein are illustrated different practical embodiments of. the invention and wherein like characters of reference denote corresponding parts in the different views:

Figure 1 is an end elevation of a friction gear according to one embodiment of the invention.

Figure 2 is a section on the line 2 2 of Figure 1.

Figure 3 is a transverse section through a ,friction gear according to another embodiment of the invention.

Figure 4 is a lsection on the line 4--4 of Figure 3.

Figure I5 is a transverse section through a friction gear according to another embodiment of the'invention.

Figure 6 is a section on the Figure 5.

Figure 7 is a transverse' section through a friction gear according to still another embodiment of the invention; and

Figure 8 is a section on the line 8 8 of Figure 7.

Referring to the drawings in detail, irst with particular reference to the practical embodiment of the invention illustrated in Figures 1 and 2, I0 and .IlA designate a pair of axially alined shafts, either of which may be the driving shaft and the other the driven shaft of the,

gear. These shafts are journaled in bearings I2 and I3, respectively, and, in the present 1nstance, the shaft Il is hollow and receives the free end portion of the shaft I0, thus to assist in maintaining axial alinementof said shafts. On said shafts are fixed friction wheels Il and I5, respectively.

Journaled on the shaft I0 for rotation relative thereto is a member I6 having shaft elements I1,

I1' which are disposed at'opposite sides of the shaft I0 and which are axially alined and have their common axis intersecting the axis of the shaft I0 at right angles thereto and between) the friction wheels I4, I 5. Onthese shaft elements are journaled, both for rotation relative thereto and for sliding movement therealong, friction disks I8, I8', respectively,` having hat inner faces with which. are engaged the peripheries of the friction wheels I4 and I5. I

Assuming that the shaftvelements I1, I1'` are held against revolving about the shaft I0 and 'that the friction disks I8, I8' are urged against the friction wheels I4, I5, it is apparent that rotation of either shaft I0 or II will result in rotation of the friction disks I8, I8' in opposite directions by the related friction wheel I4 or I5 as the case may be, with consequent rotation of the other friction wheel and the shaft by which it is carried in a direction counter to the direction of rotation of the rst shaft, and that for any given speed of the first shaft the other shaft will be rotated at a rate of speed which is dependent upon the distances of the friction wheels I4, I5 from the common axis of the friction disks I8, I8'. In other words, the gear ratio of a gear of the type illustrated may be varied by varying the distances between the friction wheels I4, I 5 and the common axis of the friction disks I8, I8', and in accordance. with the invention this may be done in any suitable manner, either by shifting the friction wheels I4, yI5 axially relative to the friction disks I8, I8', or by shifting said friction disks parallel to the common axis of the shafts IU, II.

Mounted on the shaft elements I1, I1' outwardly of the friction disks I8, I8' are race elements I9, I9', respectively, and between said race elements and said friction disks are interposed anti-friction balls 20,' 20', respectively. Also mounted on the shaft elements I1, I1', outwardly of the race elements I9, I9', are disks 2l, 2l', respectively, and, as shown, said disks have convex spherical inner surfaces against which seat companion convex outer spherical surfaces of the race elements I9, I9. Outwardly of the disks 2I, 2| the shaft elements I1, I1' have slidably mounted thereon washers 22, 22', respectively, while threaded on said shaft elements, outwardly of said washers are nuts 23, 23', respectively. Between the washers 22, 22 and the nuts 23,

'23 are interposed coil springs 24, 24', respectively, While between the disks 2|, 2l and said washers are interposed the end portions of levers 25, 25', respectively. The said end portions of said levers are provided at their inner sides with protuberances 26 which engage in notches in the outer faces of the disks 2l, 2I, respectively, while at their outer sides they are each provided with a pair of protuberances 21, 21 disposed to opposite sides of the shaft elements I1, I1' in the direction of extent of' the levers. Moreover, at their outer ends said levers are connected by links 28, 28', respectively, with the ends of a lever 29 which has a fixed intermediate pivot 30. Obviously, rocking movement of either lever in either direction results in one 0r the other of the protuberances 21 fulcruming against the related washer 22 or 22' and the protuberance 26 fulcruming against the related disk 2|l .or 2I', with consequent inward pressure of the related friction disk I8 or I8' against the friction wheels I4, I5. Obviously, too, due to the equali-zing connection between said levers, rocking of either lever results in rocking of the other lever so that both friction disks I8, I8' always are subjected to the same inward pressure. Furthermore, it is apparent that rotation of the member I6 about the common axis of the shafts I0, II is effective to rock the levers 25, 25'.

Now, assuming a normal status of the gear as illustrated in the drawings and according to which status the friction disks I8, I8 are urged against the peripheries of the friction wheels under a normal pressure which is determined by z5. the compression of the springs 24, 24' by the nuts 23, 23', it is apparent that if, for example, the shaft I0 is subjected to rotation in the direction of the arrow a in Figure 1, the friction disks I8, I8' and, conjointly therewith, the shaft elements I1, I1' and the thrust levers 25, 25' will tendl to rotate in the same direction about the common axis of the shafts I0, I I. Since, however, the pivot 30 of the lever 29 is fixed, the tendency of the levers ,25, 25' to rotate bodily will be resisted and said levers will be caused to partake of rocking motions in the directions of the arrows b in Figure 1, with the result that the friction disks will be urged inwardly against the friction wheels under a pressure which is proportional to the torque to which the gear is subjected for any ratio of the gear. In other words, an arrangement as shown and described assures a constant relationship between the pressure force and the circumferential force for each of the points of contact between the friction wheels and the friction disks, regardless of the relative positions of the friction` wheels and disks, so that, no matter what may be the speed ratio between said wheels and disks, slippage of the gearing or the imposition of inadmissibly high loads thereon is avoided, assuming, of course, a selection of the dimensions of the active leverages of the lever system to obtain;

Y pressures best suited to obtain optimum elciency of the gear.

The race elements I9, I9' are more or less loosely mounted on the shaft elements I1, I1' whereby they may partake of universal sliding movements relative to their supporting disks 2i, 2|. Thus, due to the coacting spherical formation of the adjacent or engaging faces of said race elements and their supporting disks, said race elements are self-adjusting to distribute the force applied by the levers 25, 25' upon the points of contact between the friction wheels and the friction disks at the ratio of the distances of said points from the common axis of the friction disks.

According to the arrangement illustrated in Figures 1 and 2 the member I6 precludes contacting of the centers of the friction disks I8, I8' by the friction wheels I4, I5. Therefore, the gear has a limited speed ratio range. Moreover, when the gear is transmitting power considerable forces are imposed on the friction disks tending to move the same from their 'normal operative positions. Therefore, it is important to provide for firmly supporting said friction disks. Figures 3 and 4 of the drawings illustrate an arrangement in which the friction wheels may contact with the centers of the friction disks and' in which the friction disks are supported in' an exceptionally rm manner.

Referring in detail to the arrangement illustrated in Figures 3 and 4, Illa, Ila designate a pair-of axially alined shafts on whichare fixed friction wheels I4a, I5a, respectively. On said shafts are rotatably mounted supports 3I, 32, respectively, and between these supports is confined a thrust ring 33 which normally is maintained axially alined with the shafts IIIa, IIa byA means of lugs 34 which project inwardly from the supports 3|, 32 and engage the outer face of said ring. Disposed at opposite sides of the friction wheels I4a, I5a are friction disks I8a which have flat inner faces engaging the peripheries of said friction wheels. Moreover, each of said friction disks is provided centrally thereof with an outwardly directed stub shaft 35 which is rotatable within a sleeve -or bushing 36, each bush- Y force andthe pressure at the points of contact thrust ring 33 and having closely fitted thereon, inwardly of the thrust ring, a race element-33.

' The inner face of the thrust ring is of concave spherical form and the outer faces of the race elements 38 are of convex spherical form and seat snugly against the inner face of the thrust ring. Between each race element and the outer face of the related friction disk is interposed a series of anti-friction balls 33. The stub shafts 35 are axialy alined and their common axis intersects the common axis of the shafts lila, ila at right angles thereto, any creeping of the friction disks circumferentially with respect to the thrust ring 33 being prevented by reason of the bushings 36 snugly fitting the openings 31 in the circumferential direction of thel thrust ring, as shown in Figure 3. However, said openings 31 are slightly elongated iongitudinaly of the thrust ring as illustrated in Figure 4 whereby, due to the spherical engaging surfaces of the race elements 38 and thev thrust ring, the friction disks i8a. are self-adjusting to distribute their inward- 1y directed pressure between their points of contact with the friction wheels Ma, Ia.

Embracing the thrust ring 33 are two clamp shoes 40, 40 which are connected together at adjacent ends by a strap 4l and which, at their opposite ends, are connected by links 42 with the free end portion of a lever 43 at points spaced longitudinally thereof, said lever being mounted at its other end on a fixed pivot 44. Therefore, if the thrust ring and the clamp shoes are rol tatedl in the direction of the arrow a. in Figure 3 the clamp shoes will be contracted against the thrust ring.

The thrust ring 33 is deformable by pressure of the clamp shoes 40 thereagainst to urge the friction disks |80, inwardly under pressure against the friction wheels Ma, I5a. Hence, the lugs 34 which function to maintain the thrust ring 33 centered with respect tothe common axis of theshafts lila, lla are disposed at points as shown which experience least change in distance from the common axis of the shafts Ina, Ha under deformation of the thrust ringl by the clamp shoes 40. y

Under normal conditions the thrust ring 33 urges the friction disks |30, under suitable pressure against the friction wheels` i4a, I5'a.

Assuming that either shaft lila or Ila is rotated in the direction of the arrow a in Figure 3,

it is apparent from the foregoing that the friction disks |811., the thrust ring 33 andthe clamp shoes 40 will tend to rotate with said shaft and that as a consequence the clamp shoes will be contracted against the thrust ring and willhold it against rotation and, at the same time, will exert a deforming pressure thereon which is re' fiected in like pressure of the friction disks .against the friction wheels and which is proportional to the torque to which the gear is subjected for any ratio of the gear. Thus, by choosing suitable dimensions for the effective leverages of the lever system of the gear, optimum` efflciency relationship between the circumferential of the friction disks with the friction wheels, and which is preserved for all speed ratios 4of the gear, can be obtained.

If the thrust ring 33 is permitted torotate the vgear obviously will not transmit power, since the friction disks 13a will simply rotate idly 'about the friction wheels' Ila, lia.` Consequently, the gear is useful as a clutch to be actuated-byv holding and releasing the thrust ring according to' requirements.

Manifestly, according to the construction il- 1ustrated in Figures 3 and 4 the thrust ring 33 affords a firm support for the friction disks I8a effectively holding them against movement from their operative positions. Moreover, because of the mounting of the friction disks in the manner shown, the space between said disks is unobstructed so that the gear may be adjusted to bring either of the friction wheels I4a, |5a into contact with the centers of said friction disks.

Figures 5 and 6 of the drawings illustrate an arrangement which is quite similar to the arrangement illustrated in `Figures 3 and-4, but which is especially meritorious because it avoids the necessity of providing special means' to center driving and the driven shafts of the gear.

Referring in detail to the arrangement illustrated in Figures 5'and 6, illb, IIb designate a pair of shafts which are axially alined and carry friction wheels Mb, ib, respectively, 4and .either of which may be the driving shaft and the other the driven shaft of the gear. Coaxial with said shafts is a thrust ring 33h which, for simplicity of construction and for facile assembly ofthe gear, is formed in two half sections which may be riveted, bolted or otherwise suitably secured together. Three friction disks i8b are provided according to this embodiment of the invention and, as in the case of the first two embodiments of the invention, Athese friction disks' have flat. inner faces which engage the peripheries of the friction wheels i4b, i312. The friction disks ib are spaced apart equal angular distances about the friction disk carrying ring relative to the l the common axis` of theA shafts iiib, ilb with their axes in a common plane at right angles to the said common axis of said shafts and, moreover, said friction disks are disposed with their axes intersecting the common axis of the shafts Illb, Hb. Each disk is provided with an outwardly extending stub shaft 35b which is journaled in'a sleeve or bushing 3617` and the outer end portion of each sleeve or bushing is accommodated within an opening 31b inthe thrust ring 33h inthe same manner as set forth in connection with the Figures 3 and 4 embodiment of the invention. Moreover, the inner face of the thrust ring 33h is of'concave spherical form and' on each bushing 36h is snugly fitted a race element 38h having a convex spherical-outer face engaging the inner face of the thrust ring, while between each race element and the related friction ydisk Ib is a series of anti-friction balls 39h.

`The ring 33h is split as indicated at 45, and at' each of the two ring ends thus formed is an outwardly projecting lug '46. Embracing said lugs is a yoke 41, and between one of said lugs 4is refiected in intensification of the pressure'of said friction disks against the friction wheels I4b, lib.

Thegear according to the Figures 5, 6 embodiment may be adjusted as set forth in connection with the Figures 1 to 4 embodiments to vary its ratio, and for any ratio of adjust- `nient `thereof the pressure of the friction disks |8b against the friction wheels Mb, |5b obviously is proportional to the torque transmitted.

Obviously, too, because of the use of three friction disks |8b arranged as shown and described, the thrust ring 33o is held centered with respect to the common axis of the shafts |b, ||b and the provision of any auxiliary means for this purpose is rendered entirely unnecessary.

According to each of the foregoing embodiments of the invention the arrangement is such that the driving and driven shafts of the gear rotate in opposite directions. As distinguished from this, Figures '7 and 8 of the drawings illustrate an embodiment of the invention in which the driving and driven shafts rotate in the same direction.

Referring in detail to Figures 7 and 8 of the drawings, Ille, ||c designate axially alined driving and driven shafts, respectively', the former of which has fixed thereon a friction wheel Mc.

On the other hand, the second friction wheel -|8c are spaced equal angular distances about the 'common axis of the shafts |0c, Hc, and 50i and they are disposed with their axes in a common plane at rightangles to the common axis of the shafts lc, llc, and l). Moreover,

said friction disks are disposed with their axes l intersecting the common axis of the shafts |Uc, llc, and 5|] and with their inner flat faces engaging the peripheries of the friction wheels |40, l5c. In addition they are mounted within a thrust Vring 33e in the same manner as shown and described with reference to the Figures 3 to 6 embodiments of the invention.

The thrust ring 33e is split as indicated at 45o and at one of the ring ends thus formed is an outwardly projecting lug 46c. Fixed to the other ring end is a member 54 which extends over the rst mentioned ring end and which is provided with an inwardly directed lug 55. Between the lugs 46c, 55 is interposed a cam bar 56 which, by rotation, forces said lugs apart and effects contraction of the thrust ring 33e.

Splined on the shaft llc, as at 51, is a collar 58 having arms 59 engaging the ring 33e so that a constant operative relationship is maintained between the collar and said ring'. The collar is provided with a radial slot, as indicated at 60, and the cam bar 55 is provided with a crank arm 6| having a pin 62 which is engaged in said slot 60. Thus, if the collar 58 is rotated relative to the ring 33o, the cam bar 56 is rotated due to the connection of its arm 6| with the collar and as a consequence the lugs 46c, 55 are forced apart, thereby contractingthe ring 33e and intensifying the pressure of the friction disks |8c against the friction wheels |4c, |5c.

According to the Figures 7, 8 construction regulation of the gear to vary its ratio is effected byl shifting the collar 58 along the shaft llc, and ,this may be done in any suitable manner. Shifting of the collar results in shifting of the ring 33o and consequent shifting of the friction disks l8r: relative to the friction wheels Mc, |5c.

If the shaft Ic is driven and the brake band 53 is released, rotation of the friction wheel |4c will be transmitted through the friction disks |8c to the friction wheel |5c and the direction of rotation of the latter will be counter to the direction of rotation of the wheel |40. The gear thus will idle, regardless of the relative positions of the friction wheels and the friction disks. If, on the other hand, the brake band 53 is actuated to hold the drum 52 and thereby the friction wheel |5c against rotation, then rotation of the shaft |0c and the friction wheel |4c will result in planetation of the friction disks |8c and the ring 33e about the friction wheel |5c at a rate of speed which is dependent upon the distances of the contact points between the wheels |4c, |5c and the disks |8c from the centers of the disks |8c. Rotation of the ring 33o will be transmitted through the cam bar 56 and its crank arm 6| to the collar 56 and thereby the shaft ||c will be rotated in the same direction as the shaft |0c and at the same speed as the ring 33o. Since rotation of the ring 33e is transmitted to the collar 58 and the shaft ||c through the crank arm 6|, and since swinging of said crank arm results in contraction of the ring 33c, it follows that the friction disks are forced against the friction wheels under a pressure which is proportional to the torque transmitted through the gear for will be clearly understood. It is desired to point out, however, that while only certain specific structural embodiments of the invention have been illustrated and described, the invention is readily capable of embodiment in various other 'mechanical structures within the spirit and the scope thereof as defined in the appended claims.

I claimt 1. In combination, a friction gear comprising a pair of axially aligned shafts, a friction wheel on each shaft, friction discs rotatable in planes substantially parallel to the common axis of said shafts and engaging the peripheries of the friction wheels for transmitting power therebetween, means for mounting said friction discs whereby they are adapted to move toward the friction wheels, and to pivot about the axis of said shafts, and means adapted to convert the pivotal movement of said discs due to the peripheral force exerted on the friction discs by the friction wheels and-tending to turn the friction discs about the common axis of the shafts into a force causing movement of and pressing the friction discs against the friction wheels.

2. In combination, a friction gear comprising a pair of axially aligned shafts, a friction wheel on each shaft, friction discs rotatable in planes substantially parallel to the common axis of said shafts and engaging the peripheries of the friction wheels'for transmitting power therebetween, means for mounting said friction discs so that they are adapted to move toward the friction wheels and to pivot about the axis of said shafts, clamp means operable when actuated to press the friction discs against the friction wheels, and means adapted to convert the pivotal movement of said'discs due to the peripheral force exerted 'on the friction discs by the friction wheels and tending to rotate the friction wheels about the common axis of the shafts into a force causing said clamp means topress the friction discs against the friction Wheels.

3. A friction gear as set forth in claim l in which said mounting means includes a carrier rotatably mounted on oneof the shafts and in ,A which the friction discs are mounted on said carrier.

4. A friction gear as set forth in claim l in which said mounting means includes a ring disposed substantially axially alined with the common axis of the shafts and in which the friction disks are mounted onsaid ring within the same.

as to be rotatable in planes substantially parallel to the common axis of the shafts and so as to engage the peripheries of said friction wheels, means whereby contraction of said ring presses the friction disks against the friction wheels,

' and -means adapted to cause the tendency of the friction wheels and ring to rotate about the common 'axis of the shafts under the influence of rotation of the friction wheels to contract said ring.

7. A friction gear as set forth in .claim I in rier for the friction discs, and means mounting each friction Adisc on saidicarrier for selfadjustment with respect thereto in a plane including the common axis of the shafts and the axis of the friction discs.

8. A friction gear as set forth in claim 1 com'- prising more than two friction, disks spaced apart equal angular distances about the coin-A mon axis of the shafts.

9. A friction gear as set forth in claim 1 including means for releasably securing one of the friction wheels against rotation.

10. A friction gear comprising a pair of axially alined shafts, a friction wheel on each shaft, a deformable ring, supports on the shafts holding the ring substantially axially alined with the shafts, friction disks carried by the ring within the same, said disks engaging the peripheries of the frictionl wheels and being rotatable in planes parallel with respect to the common axis of the shafts and movable toward the friction wheels, means adapted to cause deformation of the ring to press the disks against said wheels, clamp shoes embracing the ring, and lever means connecting said clamp shoes adapted to cause, the tendency of the disks and ring to rotate with the wheels actuate said shoes to deform the ring.

11. A friction gear as set forth in claim l0 including a mounting for each friction disk whereby it is adapted for self-adjustment againstthe friction wheels in a plane including `the axis of the disk and `the common axis of on axes radial with respect to said shafts.

means whereby contraction of said ring presses.

the disks against the wheels, and lever means operable in response to tendency of the disks and the ring to rotate with the wheels to contract said ring.

13. A friction gear as set forth in claim 12 including a mounting for each friction disk `whereby itis adapted for self-adjustment alined with said shafts, friction disks mounted on said ring within the same, said disks engaging the peripheries of said wheels and being rotatable on axes radial with respect to said shafts, means whereby contraction of said ring presses the disks against the wheels,\a cranked member operable `by rotation to contract said ring, and a connection between said cranked member and the shaft which is devoid of a friction Wheel whereby rotation of the ring ,is im.-

parted to the latter shaft and whereby the tendency of the crank to rotate under the. transmission of torque contracts said ring.

16. A friction gear as set forth in claim 15 including a mounting for each friction disk whereby it is adapted for self-adjustment against the friction wheels in a plane including the axis` of the disk and the common axis ofthe shafts.

17. A friction gear as set forth in claim 15 in which an element is coupled with the ring and splined to the shaft which is devoidr ofl a frictio'n wheeLand in which the cranked member is connected with said element.

18. In combination, a gear comprising a pair of axially alined shafts, a friction wheel on each shaft, friction discs rotatable in planes substantially parallel to the common axis o f said shafts and engaging the peripheries of the friction wheels for transmitting power therebetween, a mounting for said friction discs whereby they are adapted to move toward the friction wheels, and to pivot about the common axis of the shafts, and means adapted to convert the peripheral force exerted on the friction discs by the friction wheels and causing turning of the friction discs about the common axis of the shafts into a force causing movement of and pressing the friction discs against the friction wheels.

19. In combination, a gear comprising a pair of axially alined shafts, a friction wheel on each shaft, a pair of friction discs rotatable in planes substantially parallel to the common axis of said shafts and engaging the peripheries of the friction wheels for transmitting power therebetween, a mounting for said friction discs whereby they `are adapted to move toward the friction wheels,

and to pivot about the common axis of the shafts, clamp means operable when actuated to press the friction discs against the friction wheels, and means adapted to convert the pivotal movement of said friction discs about the said common axis of the shafts\\as a result of the peripheral force exerted on the friction discs by the friction wheels and tending to rotate the friction discs about the common axis of the shafts into a force causing actuation of said clamp to press the friction discs `against the friction wheels.

20. In combination a friction gear comprising a pair of axially aligned shafts, a friction wheel on each shaft, friction discs rotatable in planes substantially parallel to the common axis of said shafts and engaging the peripheries of the friction wheels for transmitting power therebetween, a mounting for each of said friction discs whereby they are adapted to move toward or away from the friction wheels and also pivotally about the axis of said wheels and means adapted to convert the pivotal movement resulting from the peripheral force exerted on the friction discs by the friction wheels and tending to turn the friction discs about the common axis of the shafts into aA movement causing said friction discs to `press against the friction wheels.

21. In combination, a friction gear comprising a pair of axially aligned shafts, one being a driven shaft and the other a driving shaft, a friction wheel on each shaft, friction discs ro- "tatable in planes substantially parallel to the the axis of said shafts, and means adapted to convert the peripheral force exerted on the friction discs by the friction wheels and causing turni-ng of the friction discs about the common axis of the shafts, into a force causing movement of and pressing the friction discs against the friction wheels.

22. In combination a friction gear comprising a pair of laxially aligned shafts, one being a driven shaft and the other a driving shaft, a friction wheel on each shaft, friction discs rotatable in planes substantially parallel to the common axis of said shafts and engaging the peripheries of the friction wheels for transmitting power therebetween, means for mounting said friction discs whereby they are adapted to move toward the friction wheels in either direction, and to pivot about the axis of said shafts in either direction and means adapted to convert the peripheral force exerted on the friction discs by the friction wheels, in either direction of rotation thereof, and causing turning of the friction discs about the common axis of the shafts into a force causing movement of and pressing the friction discs against the friction wheels, whereby said means will be operative to cause pressure of the friction discs against said friction wheels, in either direction of rotationl of said driving friction wheel.

RICHARD ERBAN. 

